JP3462265B2 - Wavelength conversion element - Google Patents
Wavelength conversion elementInfo
- Publication number
- JP3462265B2 JP3462265B2 JP13901294A JP13901294A JP3462265B2 JP 3462265 B2 JP3462265 B2 JP 3462265B2 JP 13901294 A JP13901294 A JP 13901294A JP 13901294 A JP13901294 A JP 13901294A JP 3462265 B2 JP3462265 B2 JP 3462265B2
- Authority
- JP
- Japan
- Prior art keywords
- conversion element
- wavelength conversion
- epitaxial
- substrate
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/37—Non-linear optics for second-harmonic generation
- G02F1/377—Non-linear optics for second-harmonic generation in an optical waveguide structure
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
- G02F1/3544—Particular phase matching techniques
- G02F1/3548—Quasi phase matching [QPM], e.g. using a periodic domain inverted structure
Description
【０００１】[0001]
【産業上の利用分野】本発明は、第２高調波発生(Secon
d Harmonic Generation:SHG）を利用した非線形光学結
晶の導波路を有する波長変換素子に関する。The present invention relates to the second harmonic generation (Secon
The present invention relates to a wavelength conversion element having a waveguide of a nonlinear optical crystal using d Harmonic Generation (SHG).
【０００２】[0002]
【従来の技術】波長変換素子において、第２高調波発生
を効率よく発生するためには位相整合条件を満たす必要
がある。位相整合方法には、波長変換素子の基板結晶の
複屈折性を利用し角度同調、温度同調、電界同調を用い
て位相整合条件を満たす方法や、導波路のモード分散を
用いることにより、導波路の膜厚、オーバーレイヤ、チ
ェレンコフ放射、疑似位相整合など、種々の方法が試み
られている。2. Description of the Related Art In a wavelength conversion element, it is necessary to satisfy a phase matching condition in order to efficiently generate the second harmonic. The phase matching method uses the birefringence of the substrate crystal of the wavelength conversion element to satisfy the phase matching condition by using the angle tuning, the temperature tuning, and the electric field tuning, and the mode dispersion of the waveguide. Various methods such as film thickness, overlayer, Cherenkov radiation, and quasi phase matching have been tried.
【０００３】波長変換素子の基板には、ＬｉＴａＯ
3（以下、ＬＴという）、ＬｉＮｂＯ3（以下、ＬＮとい
う）、ＫＴｉＯＰＯ4等の非線形光学定数の大きい強誘
電体が好ましく用いられている。例えば、ＬｉＮｂ1-x
ＴａxＯ2（０≦ｘ≦１）（以下、ＬＮＴという）のバル
ク結晶は融液から引上げるＣＺ法、ＴＳＳＧ法やノズル
を使って結晶を引き下げるマイクロ結晶作製法などで形
成される。しかし、その結晶の高品質化、高均一化、大
型化、導波路化などには難点があった。そこで、ＬＮＴ
結晶薄膜をサファイア等の基板上に形成するスパッタリ
ング法が開発されている。LiTaO is used as the substrate of the wavelength conversion element.
Ferroelectric materials having large nonlinear optical constants such as 3 (hereinafter referred to as LT), LiNbO 3 (hereinafter referred to as LN), and KTiOPO 4 are preferably used. For example, LiNb 1-x
A bulk crystal of Ta x O 2 (0 ≦ x ≦ 1) (hereinafter referred to as LNT) is formed by a CZ method of pulling up from a melt, a TSSG method, a microcrystal manufacturing method of pulling down a crystal by using a nozzle, or the like. However, there have been difficulties in improving the quality of the crystal, making it highly uniform, increasing the size, and forming a waveguide. So LNT
A sputtering method for forming a crystal thin film on a substrate such as sapphire has been developed.
【０００４】また、プラズマ気相成長法によりサファイ
ア基板上にＬＮＴの単結晶膜を作成する方法も、開発さ
れている（特公平５−１１０７８号公報）。これは酸素
プラズマ中でＬｉ、Ｔａ、Ｎｂを酸化させサファイア基
板上にＬＮＴ単結晶膜をエピタキシャル成長させて堆積
している。A method of forming a single crystal film of LNT on a sapphire substrate by plasma vapor deposition has also been developed (Japanese Patent Publication No. 5-11078). In this method, Li, Ta and Nb are oxidized in oxygen plasma, and an LNT single crystal film is epitaxially grown and deposited on a sapphire substrate.
【０００５】[0005]
【発明が解決しようとする課題】ＬＮＴは高融点、高キ
ュリー点の強誘電体であって、さらに他の強誘電体より
も電機機械結合係数が大きいことが知られている。さら
にＬＮＴは非線形光学定数も大きいので、波長変換素子
の使用に適している。しかしながら、これら諸特性がさ
らに高い強誘電体が波長変換素子の導波路のためには望
まれている。It is known that LNT is a ferroelectric substance having a high melting point and a high Curie point, and has a larger electromechanical coupling coefficient than other ferroelectric substances. Furthermore, since LNT has a large nonlinear optical constant, it is suitable for use as a wavelength conversion element. However, a ferroelectric having higher characteristics is desired for the waveguide of the wavelength conversion element.
【０００６】そこで、本発明の目的は、有機金属気相エ
ピタキシ（以下、ＭＯＣＶＤという）法によって、基板
上にＬＮＴに代るＫＬｉＮｂＴａＯ系エピタキシャル層
を有した基板からなる波長変換素子を提供することにあ
る。Therefore, an object of the present invention is to provide a wavelength conversion element comprising a substrate having a KLiNbTaO-based epitaxial layer replacing LNT on the substrate by a metal organic vapor phase epitaxy (hereinafter referred to as MOCVD) method. is there.
【０００７】[0007]
【課題を解決するための手段】本発明の波長変換素子
は、基板と、前記基板の表面に堆積されたＫ3Ｌｉ2-xＮ
ｂ5+x-yＴａyＯ15+2x（−０．４≦ｘ≦０．２０，０≦
ｙ≦０．３３）のエピタキシャルクラッド層と、前記エ
ピタキシャルクラッド層上に堆積されたＫ3Ｌｉ2-x'Ｎ
ｂ5+x'-y 'ＴａyＯ15+2x'（−０．４≦ｘ’≦０．２
０，０≦ｙ’≦０．３３）からなり前記エピタキシャル
クラッド層よりも屈折率の大きいエピタキシャル導波路
層と、からなり、前記エピタキシャルクラッド層と前記
エピタキシャル導波路層が、少なくともリチウム（Ｌ
ｉ）、カリウム（Ｋ）、タンタル（Ｔａ）及びニオブ
（Ｎｂ）の有機金属化合物ガスの各々を有機金属気相エ
ピタキシ装置の成長室に配置された前記基板上へ導入
し、前記有機金属化合物ガスの反応により、形成されて
いる、ことを特徴とする。The wavelength conversion element of the present invention comprises a substrate and K 3 Li 2-x N deposited on the surface of the substrate.
b 5 + xy Ta y O 15 + 2x (−0.4 ≦ x ≦ 0.20, 0 ≦
y ≦ 0.33), and K 3 Li 2−x ′ N deposited on the epitaxial clad layer
b 5 + x'-y 'Ta y O 15 + 2x' (-0.4 ≦ x '≦ 0.2
And 0,0 ≦ y '≦ 0.33) made from the epitaxial cladding layer greater epitaxial waveguide layer having a refractive index higher than, Ri Tona, wherein said epitaxial cladding layer
The epitaxial waveguide layer is at least lithium (L
i), potassium (K), tantalum (Ta) and niobium
Each of the (Nb) organometallic compound gases is treated with an organometallic vapor phase gas.
Introduced on the substrate placed in the growth chamber of the pitax machine
Formed by the reaction of the organometallic compound gas
It is characterized by
【０００８】[0008]
【実施例】以下に、本発明による実施例を図面を参照し
つつ説明する。発明者は、ＭＯＣＶＤ法によって基板上
にＬＮＴに代るＫＬｉＮｂＴａＯ系エピタキシャル層を
形成し、このエピタキシャル層が波長変換素子に適する
導波路となることを知見し本発明に到った。Embodiments of the present invention will be described below with reference to the drawings. The inventor has arrived at the present invention by discovering that a KLiNbTaO-based epitaxial layer that replaces LNT is formed on a substrate by the MOCVD method, and that this epitaxial layer serves as a waveguide suitable for a wavelength conversion element.
【０００９】すなわち、ＭＯＣＶＤ装置の反応室に基板
を装填し、これを設定温度まで昇温して反応室内部を設
定気圧まで減圧し、またＭＯＣＶＤ装置の気化器のそれ
ぞれに出発原料として、ジピバロイルメタナトカリウム
［Ｋ（Ｃ11Ｈ19Ｏ2）］（以下、Ｋ（ＤＰＭ）という）
と、ジピバロイルメタナトリチウム［Ｌｉ（Ｃ11Ｈ19Ｏ
2）］（以下、Ｌｉ（ＤＰＭ）という）と、トリクロロ
ビス（ジピバロイルメタナト）ニオブ(V) ［Ｎｂ（Ｃ
11Ｈ19Ｏ2）2Cl3］（以下、Ｎｂ（ＤＰＭ）2Cl3とい
う）と、ジピバロイルメタナトタンタル［Ｔａ（Ｃ11Ｈ
19Ｏ2）］（以下、Ｔａ（ＤＰＭ）という）と、を装填
して、これら出発原料をそれぞれ設定温度に保つことに
より昇華させ有機金属化合物ガスとし、ガスを流量制御
されたＡｒキャリアガスを用いて加熱基板が配置された
反応室へ導き、原料ガスを基板上に流すことによりＫＬ
ｉＮｂＴａＯ系エピタキシャル単結晶薄膜、Ｋ3Ｌｉ2-x
Ｎｂ5+ x-yＴａyＯ15+2xなる式で表される組成を持つ結
晶薄膜が成長できた。そして、基板上のエピタキシャル
層の成分の原子比変えて２層のエピタキシャル単結晶薄
膜を成膜し、エピタキシャル導波路を形成した波長変換
素子を作成した。That is, a substrate is loaded into the reaction chamber of the MOCVD apparatus, the temperature of the substrate is raised to a set temperature to reduce the pressure inside the reaction chamber to the set atmospheric pressure, and the vaporizer of the MOCVD apparatus is used as a starting material with dipyrene. Baroylmethanatopotassium [K (C 11 H 19 O 2 )] (hereinafter referred to as K (DPM))
And dipivaloylmethanatolithium [Li (C 11 H 19 O
2 )] (hereinafter referred to as Li (DPM)) and trichlorobis (dipivaloylmethanato) niobium (V) [Nb (C
11 H 19 O 2 ) 2 Cl 3 ] (hereinafter referred to as Nb (DPM) 2 Cl 3 ) and dipivaloylmethanatotantalum [Ta (C 11 H 2
19 O 2 )] (hereinafter referred to as Ta (DPM)), and these starting materials are each sublimated by maintaining a preset temperature to be an organometallic compound gas, and the gas is an Ar carrier gas whose flow rate is controlled. It is used to guide the heating substrate to the reaction chamber where it is placed, and the source gas is flowed over the substrate to produce KL.
iNbTaO-based epitaxial single crystal thin film, K 3 Li 2-x
A crystal thin film having a composition represented by the formula Nb 5+ xy Ta y O 15 + 2x could be grown. Then, two layers of epitaxial single crystal thin films were formed by changing the atomic ratio of the components of the epitaxial layer on the substrate, and a wavelength conversion element having an epitaxial waveguide was formed.
【００１０】さらに具体的には、出発原料として、Ｋ
（ＤＰＭ）、Ｌｉ（ＤＰＭ）、Ｎｂ（ＤＰＭ）2Cl3及び
Ｔａ（ＤＰＭ）を個別にベローズバルブ付きステンレス
スチール製気化器に封入してＣＶＤソースとした。これ
ら原料をそれぞれ恒温空気浴槽中で設定温度に対して±
１℃以内に保ちつつ、１６０Torrの減圧下で昇華させ流
量調整されたＡｒキャリアガスを用いてフローチャネル
の付いた横型反応装置へ供給した。More specifically, as a starting material, K
(DPM), Li (DPM), Nb (DPM) 2 Cl 3 and Ta (DPM) were individually enclosed in a stainless steel vaporizer with a bellows valve to form a CVD source. Each of these raw materials was
While maintaining the temperature within 1 ° C., an Ar carrier gas which was sublimated under a reduced pressure of 160 Torr and whose flow rate was adjusted was supplied to a horizontal reactor equipped with a flow channel.
【００１１】恒温空気浴槽の設定温度はそれぞれ、Ｋ
（ＤＰＭ）が１８０℃〜２００℃、Ｌｉ（ＤＰＭ）が１
８０℃〜２１０℃、Ｎｂ（ＤＰＭ）2Cl3が１７０℃〜１
９０℃、及びＴａ（ＤＰＭ）が１６０℃〜１９０℃の温
度範囲から適宜選ばれた。反応装置中にはインコネルの
サセプター上に石英トレイを置きその上に基板を配置
し、高周波加熱によって約５００℃〜７００℃で加熱し
た。鏡面研磨した基板を用いた。The set temperature of the constant temperature air bath is K
(DPM) is 180 ° C to 200 ° C, Li (DPM) is 1
80 ° C to 210 ° C, Nb (DPM) 2 Cl 3 is 170 ° C to 1
90 degreeC and Ta (DPM) were suitably selected from the temperature range of 160 degreeC-190 degreeC. A quartz tray was placed on an Inconel susceptor in the reactor, a substrate was placed thereon, and heating was performed at about 500 ° C. to 700 ° C. by high frequency heating. A mirror-polished substrate was used.
【００１２】Ａｒキャリアガスに導かれた原料ガスある
いはそれらの混合物を、加熱基板の置かれたリアクタ内
に層流として流し、この基板上に、種々のエピタキシャ
ルクラッド層を析出させた。この時のそれぞれの原料に
対するＡｒキャリアガスの流量は、Ｋ（ＤＰＭ）では２
００〜４００ｍｌ／分、Ｌｉ（ＤＰＭ）では１００〜２
００ｍｌ／分、Ｎｂ（ＤＰＭ）2Cl3では５〜１３０ｍｌ
／分、及びＴａ（ＤＰＭ）では０〜６０ｍｌ／分の範囲
から適宜選ばれた。また、出発原料からの各酸化物の生
成には酸化反応をともなうため、反応ガスに一定量の酸
素を２００〜４００ｍｌ／分程度添加した。なお、ガス
系はステンレススチールで配管し、真空系に連結してリ
ークバルブにより反応系の圧力を調整した。A raw material gas introduced into an Ar carrier gas or a mixture thereof was caused to flow as a laminar flow in a reactor on which a heating substrate was placed, and various epitaxial cladding layers were deposited on this substrate. The flow rate of Ar carrier gas for each raw material at this time is 2 in K (DPM).
00-400 ml / min, 100-2 for Li (DPM)
00 ml / min, Nb (DPM) 2 Cl 3 5-130 ml
/ Min, and Ta (DPM) was appropriately selected from the range of 0 to 60 ml / min. In addition, since the formation of each oxide from the starting material involves an oxidation reaction, a fixed amount of oxygen was added to the reaction gas at about 200 to 400 ml / min. The gas system was made of stainless steel, connected to a vacuum system, and the pressure of the reaction system was adjusted by a leak valve.
【００１３】図１に示すように、基板１には、例えばＫ
3Ｌｉ2Ｎｂ5Ｏ15等のＫ3Ｌｉ2-x''Ｎｂ5+x''Ｏ15+2x''
（−0.4≦ｘ''≦0.20，ｘ＋0.0005≦ｘ''≦ｘ＋0.005，
ｘ≠ｘ''≠ｘ'）、Ｂａ6Ｎｂ8Ｔｉ2Ｏ30、Ｂａ5Ｔａ10
Ｏ30またはＫ2ＢｉＮｂ5Ｏ15の結晶基板を用い、それぞ
れの＋ｃ面もしくは−ｃ面上にＫ3Ｌｉ2-xＮｂ5+x-yＴ
ａyＯ15+2xなる組成を持つエピタキシャルクラッド層２
を成長させ、さらにこエピタキシャルクラッド層の上へ
Ｋ3Ｌｉ2-x'Ｎｂ5+x'-y'ＴａyＯ15+2x'なる組成で表さ
れエピタキシャルクラッド層２より屈折率の大きいエピ
タキシャル導波路層３を成長させてスラブ導波路とし
た。As shown in FIG. 1, the substrate 1 has, for example, K
K 3 Li 2 -x '' Nb 5 + x '' O 15 + 2x '' such as 3 Li 2 Nb 5 O 15
(-0.4 ≦ x ″ ≦ 0.20, x + 0.0005 ≦ x ″ ≦ x + 0.005,
x ≠ x ″ ≠ x ′), Ba 6 Nb 8 Ti 2 O 30 , Ba 5 Ta 10
A crystal substrate of O 30 or K 2 BiNb 5 O 15 is used, and K 3 Li 2−x Nb 5 + xy T on the + c plane or −c plane of each crystal substrate.
Epitaxial clad layer 2 with composition a y O 15 + 2x
On the epitaxial clad layer, and the epitaxial conductive layer having a refractive index larger than that of the epitaxial clad layer 2 and having a composition of K 3 Li 2−x ′ Nb 5 + x′−y ′ Ta y O 15 + 2x ′ is grown on the epitaxial clad layer 2. The waveguide layer 3 was grown to form a slab waveguide.
【００１４】Ｋ3Ｌｉ2-xＮｂ5+x-yＴａyＯ15+2xはタン
グステンブロンズ型の結晶をなし、基板１に用いたＫ3
Ｌｉ2Ｎｂ5Ｏ15、Ｂａ6Ｎｂ8Ｔｉ2Ｏ30、Ｂａ5Ｔａ10Ｏ
30、Ｋ2ＢｉＮｂ5Ｏ15も同じ結晶系であるため、良好な
エピタキシャルクラッド層２が成長し、その上には伝播
損失の少ないエピタキシャル導波路層３が形成できた。[0014] K 3 Li 2x Nb 5 + xy Ta y O 15 + 2x No crystals of tungsten bronze type, K 3 used for the substrate 1
Li 2 Nb 5 O 15 , Ba 6 Nb 8 Ti 2 O 30 , Ba 5 Ta 10 O
Since 30 and K 2 BiNb 5 O 15 also have the same crystal system, a good epitaxial clad layer 2 was grown, and an epitaxial waveguide layer 3 having a small propagation loss could be formed thereon.
【００１５】基本波をこの屈折率の大きいエピタキシャ
ル導波路層３に導波させることにより、良好な光閉じ込
めが達成され、高変換効率の波長変換素子が得られた。
さらに、Ｋ3Ｌｉ2-xＮｂ5+x-yＴａyＯ15+2xはＬＮ、Ｌ
Ｔ、ＬＮＴに比較して、光損傷しきい値が高いので、高
い出力まで安定した動作が得られた。Ｋ3Ｌｉ2-xＮｂ
5+x-yＴａyＯ15+2x及びＫ3Ｌｉ2-x'Ｎｂ5+x'-y'ＴａyＯ
15+2x'の両エピタキシャル層の組成に関しては、−0.4
≦ｘ≦0.20、０≦ｙ≦0.33なる範囲が望ましかった。By guiding the fundamental wave through the epitaxial waveguide layer 3 having a large refractive index, good optical confinement was achieved, and a wavelength conversion element with high conversion efficiency was obtained.
Further, K 3 Li 2x Nb 5 + xy Ta y O 15 + 2x is LN, L
As compared with T and LNT, the threshold value of optical damage is higher, so stable operation was obtained up to a high output. K 3 Li 2-x Nb
5 + xy Ta y O 15 + 2x and K 3 Li 2-x ' Nb 5 + x'-y' Ta y O
Regarding the composition of both epitaxial layers of 15 + 2x ′ , −0.4
A range of ≤x≤0.20 and 0≤y≤0.33 was desired.
【００１６】さらに基本波の波長の揺らぎや、周囲の温
度変化に対しても波長変換素子が安定に動作する為に
は、エピタキシャル導波路層３がエピタキシャルクラッ
ド層２に対して、わずかに屈折率が大きいことが必要で
ある。また、位相整合のために波長変換素子では、基本
波の波長λFと第２高調波の波長λS（＝λF／２）とに
対して、結晶膜の屈折率がほとんど等しくなるような組
成でもって結晶膜を成長させることが必要である。逆
に、結晶膜を成長させたならば、基本波の波長を選ん
で、基本波の波長λFと第２高調波の波長λSに対して、
結晶膜の屈折率がほとんど等しくなるような場合を設定
してもよい。Furthermore, in order for the wavelength conversion element to operate stably even with fluctuations in the wavelength of the fundamental wave and ambient temperature changes, the epitaxial waveguide layer 3 has a slight refractive index with respect to the epitaxial cladding layer 2. Needs to be large. Further, in the wavelength conversion element for phase matching, the refractive index of the crystal film is almost equal to the wavelength λ F of the fundamental wave and the wavelength λ S (= λ F / 2) of the second harmonic. It is necessary to grow a crystalline film with a composition. On the contrary, if the crystal film is grown, the wavelength of the fundamental wave is selected, and with respect to the wavelength λ F of the fundamental wave and the wavelength λ S of the second harmonic,
A case may be set in which the crystal films have almost the same refractive index.
【００１７】いずれの場合にも、エピタキシャル導波路
層３がエピタキシャルクラッド層２に対して、屈折率が
大きいことが必要である。このような屈折率の関係を実
現するには、エピタキシャルクラッド層２の組成を規定
するパラメータについて、ｙ＝０の場合には、ｘ＋0.00
05≦ｘ'≦ｘ＋0.005なる範囲を設定すれば良い。なお、
エピタキシャル導波路層３の膜厚については、エピタキ
シャル導波路層３は２〜４μｍが好ましく、正確には、
基本波および第２高調波の波長と、エピタキシャルクラ
ッド層２の屈折率とから、基本波の導波光が基本モード
で伝播するように定める。また、エピタキシャルクラッ
ド層２の膜厚については、導波光のエバネッセントが基
板１に漏れ出ないように少なくとも２μｍ以上は確保す
る必要がある。In any case, it is necessary that the epitaxial waveguide layer 3 has a larger refractive index than the epitaxial cladding layer 2. In order to realize such a relationship of the refractive index, the parameter defining the composition of the epitaxial cladding layer 2 is set to x + 0.00 when y = 0.
It is sufficient to set a range of 05 ≦ x ′ ≦ x + 0.005. In addition,
Regarding the film thickness of the epitaxial waveguide layer 3, the epitaxial waveguide layer 3 preferably has a thickness of 2 to 4 μm.
Based on the wavelengths of the fundamental wave and the second harmonic and the refractive index of the epitaxial cladding layer 2, it is determined that the guided light of the fundamental wave propagates in the fundamental mode. The film thickness of the epitaxial cladding layer 2 needs to be at least 2 μm or more so that the evanescent light of the guided light does not leak to the substrate 1.
【００１８】さらに、もっと安価な基板を用いてこのよ
うな波長変換素子を実現するために、第２の実施例とし
て、図２に示すように、基板１にサファイアあるいはＭ
ｇＯを用い、バッファー層４としてＫＮｂＯ3や、例え
ばＫ3Ｌｉ2Ｎｂ5Ｏ15等のＫ3Ｌｉ2-x'''Ｎｂ5+x'''Ｏ
15+2x'''（−0.4≦ｘ'''≦0.20，ｘ＋0.0005≦ｘ'''≦
ｘ＋0.005，ｘ≠ｘ'''≠ｘ'）を薄く臨界膜厚0.1〜0.3
μmで成膜し、その後に、Ｋ3Ｌｉ2-xＮｂ5+x-yＴａyＯ
15+2xなる組成を持つエピタキシャルクラッド層２を成
長させ、さらにこのエピタキシャルクラッド層２の上へ
Ｋ3Ｌｉ2-x'Ｎｂ5+x '-y'ＴａyＯ15+2x'なる組成で表さ
れるエピタキシャル導波路層３を成長させて導波路とし
波長変換素子を形成した。サファイアあるいはＭｇＯの
基板方位は、それぞれ、Ｒ面および(100)面である。こ
の第２の実施例によっても、光損傷しきい値が高く、高
出力まで安定した動作が得られる高変換効率の波長変換
素子が得られた。Furthermore, in order to realize such a wavelength conversion element using a cheaper substrate, as a second embodiment, as shown in FIG.
gO is used, and KNbO 3 as the buffer layer 4 or K 3 Li 2−x ″ ′ Nb 5 + x ″ ′ O such as K 3 Li 2 Nb 5 O 15 is used.
15 + 2x "' (-0.4≤x'" ≤0.20, x + 0.0005≤x '''≤
x + 0.005, x ≠ x '''≠x') and thin critical film thickness 0.1 to 0.3
After forming a film with a thickness of μm, K 3 Li 2-x Nb 5 + xy Ta y O
Table epitaxial cladding layer 2 is grown, further K 3 Li 2x 'Nb 5 + x' -y 'Ta y O 15 + 2x' a composition onto the epitaxial cladding layer 2 having a 15 + 2x a composition The epitaxial waveguide layer 3 thus formed was grown into a waveguide to form a wavelength conversion element. The substrate orientation of sapphire or MgO is the R plane and the (100) plane, respectively. Also according to the second embodiment, a wavelength conversion element having a high optical damage threshold value and a high conversion efficiency capable of obtaining stable operation up to a high output can be obtained.
【００１９】実際には、上記両実施例において、スラブ
導波層をエッチングによりリッジ導波路を形成するこ
と、あるいは導波層３の上にさらにＳｉＯ2をストライ
プ状に装荷する等の方法により導波路を３次元化するこ
ともできる。また、本発明によれば、上記素子の３次元
導波路に交差する周期的分極反転層を形成して、非線形
光学効果による第２高調波出力がその伝播に伴ってコヒ
ーレンス長毎に極大極小を周期的に繰返すことを利用し
て、コヒーレンス長毎に発生する分極の符号を交互に反
転させて、第２高調波の出力の加算により出力を増大さ
せる疑似位相整合（ＱＰＭ）の波長変換素子を形成でき
る。さらに導波路の膜厚、オーバーレイヤなどの種々の
位相整合方法も用いることができる。In practice, in both of the above-mentioned embodiments, the ridge waveguide is formed by etching the slab waveguide layer, or SiO 2 is further loaded on the waveguide layer 3 in a stripe shape. The waveguide can be made three-dimensional. Further, according to the present invention, a periodic domain-inverted layer intersecting the three-dimensional waveguide of the above element is formed, and the second harmonic output due to the non-linear optical effect has a maximum and a minimum for each coherence length along with its propagation. A quasi-phase matching (QPM) wavelength conversion element that alternately inverts the sign of polarization generated for each coherence length by using cyclic repetition and increases the output by adding the output of the second harmonic is used. Can be formed. Further, various phase matching methods such as the film thickness of the waveguide and the overlayer can be used.
【００２０】[0020]
【発明の効果】本発明によれば、ＭＯＣＶＤ法を用い、
基板上にＫ3Ｌｉ2-xＮｂ5+x-yＴａyＯ 15+2x単結晶薄膜
をエピタキシャル成長させることにより導波路を形成し
たので、ＬＮ、ＬＴ、ＬＮＴに比して光損傷しきい値が
高く、高出力まで安定した動作が得られる高変換効率の
波長変換素子が得られる。さらに、キャリアーガスの流
量を変えることにより、容易に、結晶組成を変えること
ができるので、導波路の屈折率、膜厚を精密に制御する
ことができ製造容易な波長変換素子が得られる。According to the present invention, the MOCVD method is used,
K on the board3Li2-xNb5 + xyTayO 15 + 2xSingle crystal thin film
To form a waveguide by epitaxially growing
Therefore, the optical damage threshold is higher than that of LN, LT, and LNT.
High conversion efficiency that can obtain stable operation up to high output
A wavelength conversion element is obtained. In addition, the carrier gas flow
Easy to change the crystal composition by changing the amount
Since it is possible to precisely control the refractive index and film thickness of the waveguide.
A wavelength conversion element that can be manufactured and is easily manufactured can be obtained.
【図１】本発明による実施例の波長変換素子の概略断面
図である。FIG. 1 is a schematic sectional view of a wavelength conversion element according to an embodiment of the present invention.
【図２】本発明による他の実施例の波長変換素子の概略
断面図である。FIG. 2 is a schematic sectional view of a wavelength conversion element of another embodiment according to the present invention.
１ 基板 ２ エピタキシャルクラッド層 ３ エピタキシャル導波路層 ４ バッファー層 1 substrate 2 Epitaxial clad layer 3 Epitaxial waveguide layer 4 buffer layers
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G02F 1/37 ＪＩＣＳＴファイル（ＪＯＩＳ)─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. 7 , DB name) G02F 1/37 JISST file (JOIS)
Claims (8)
3Ｌｉ2-xＮｂ5+x-yＴａyＯ15+2x（−０．４≦ｘ≦０．
２０，０≦ｙ≦０．３３）のエピタキシャルクラッド層
と、前記エピタキシャルクラッド層上に堆積されたＫ3
Ｌｉ2-x'Ｎｂ5+x'-y 'ＴａyＯ15+2x'（−０．４≦ｘ’
≦０．２０，０≦ｙ’≦０．３３，ｘ＋０．０００５≦
ｘ’≦ｘ＋０．００５，ｘ’≠ｘ）からなり前記エピタ
キシャルクラッド層よりも屈折率の大きいエピタキシャ
ル導波路層と、からなり、 前記エピタキシャルクラッド層と前記エピタキシャル導
波路層が、少なくともリチウム（Ｌｉ）、カリウム
（Ｋ）、タンタル（Ｔａ）及びニオブ（Ｎｂ）の有機金
属化合物ガスの各々を有機金属気相エピタキシ装置の成
長室に配置された前記基板上へ導入し、前記有機金属化
合物ガスの反応により、形成されている、 ことを特徴と
する波長変換素子。1. A substrate and K deposited on the surface of the substrate
3 Li 2−x Nb 5 + xy Ta y O 15 + 2x (−0.4 ≦ x ≦ 0.
20, 0 ≦ y ≦ 0.33) epitaxial clad layer and K 3 deposited on the epitaxial clad layer
Li 2x 'Nb 5 + x'- y' Ta y O 15 + 2x '(-0.4 ≦ x'
≦ 0.20, 0 ≦ y ′ ≦ 0.33, x + 0.0005 ≦
x '≦ x + 0.005, x ' and ≠ x) from become the epitaxial cladding layer greater epitaxial waveguide layer having a refractive index higher than, Ri Tona, the epitaxial guide and said epitaxial cladding layer
Waveguide layer is at least lithium (Li), potassium
Organic gold of (K), tantalum (Ta) and niobium (Nb)
The metal-organic vapor phase epitaxy system was constructed by
Introduced on the substrate placed in a long chamber, the metallization
A wavelength conversion element , which is formed by a reaction of a compound gas .
リチウム（Ｌｉ）、カリウム（Ｋ）、タンタル（Ｔａ）
及びニオブ（Ｎｂ）の有機化合物を昇華させたものであ
ることを特徴とする請求項１記載の波長変換素子。2. The organometallic compound gas is at least lithium (Li), potassium (K), tantalum (Ta).
The wavelength conversion element according to claim 1, which is obtained by sublimating an organic compound of niobium (Nb).
からなることを特徴とする請求項１記載の波長変換素
子。3. The wavelength conversion element according to claim 1, wherein the substrate is made of a tungsten bronze type crystal.
15+2x''（−０．４≦ｘ’’≦０．２０，ｘ＋０．００
０５≦ｘ’’≦ｘ＋０．００５，ｘ≠ｘ’’≠ｘ’）、
Ｂａ6Ｎｂ8Ｔｉ2Ｏ30、Ｂａ5Ｔａ10Ｏ30又はＫ2ＢｉＮ
ｂ5Ｏ15からなることを特徴とする請求項３記載の波長
変換素子。4. The substrate is K 3 Li 2-x ″ Nb 5 + x ″ O
15 + 2x '' (-0.4≤x''≤0.20, x + 0.00
05 ≦ x ″ ≦ x + 0.005, x ≠ x ″ ≠ x ′),
Ba 6 Nb 8 Ti 2 O 30 , Ba 5 Ta 10 O 30 or K 2 BiN
The wavelength conversion element according to claim 3 , wherein the wavelength conversion element is made of b 5 O 15 .
シウムからなり、前記基板及び前記エピタキシャルクラ
ッド層の間に臨界膜厚のＫＮｂＯ3若しくはＫ3Ｌｉ
2-x'''Ｎｂ5+x'''Ｏ15+2x'''（−０．４≦ｘ’’’≦
０．２０，ｘ＋０．０００５≦ｘ’’’≦ｘ＋０．００
５，ｘ≠ｘ’’’≠ｘ’）からなるバッファ層を有する
ことを特徴とする請求項１記載の波長変換素子。5. The substrate is made of sapphire or magnesium oxide, and has a critical film thickness of KNbO 3 or K 3 Li between the substrate and the epitaxial cladding layer.
2-x ''' Nb 5 + x''' O 15 + 2x '''(-0.4≤x''' ≤
0.20, x + 0.0005 ≦ x ′ ″ ≦ x + 0.00
5. The wavelength conversion element according to claim 1, further comprising a buffer layer composed of 5, x ≠ x ′ ″ ≠≠ x ′).
μｍの範囲内にあることを特徴とする請求項５記載の波
長変換素子。6. The thickness of the buffer layer is 0.1 to 0.3.
The wavelength conversion element according to claim 5 , wherein the wavelength conversion element is in the range of μm.
〜４μｍの範囲内にあることを特徴とする請求項１記載
の波長変換素子。7. The epitaxial waveguide layer has a film thickness of 2
The wavelength conversion element according to claim 1, wherein the wavelength conversion element is in the range of ˜4 μm.
２μｍ以上であることを特徴とする請求項１記載の波長
変換素子。8. The wavelength conversion element according to claim 1, wherein the film thickness of the epitaxial cladding layer is 2 μm or more.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13901294A JP3462265B2 (en) | 1994-06-21 | 1994-06-21 | Wavelength conversion element |
| US08/491,620 US5581396A (en) | 1994-06-21 | 1995-06-19 | Wavelength converting device having an epitaxial waveguide layer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13901294A JP3462265B2 (en) | 1994-06-21 | 1994-06-21 | Wavelength conversion element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH086083A JPH086083A (en) | 1996-01-12 |
| JP3462265B2 true JP3462265B2 (en) | 2003-11-05 |
Family
ID=15235423
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13901294A Expired - Fee Related JP3462265B2 (en) | 1994-06-21 | 1994-06-21 | Wavelength conversion element |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5581396A (en) |
| JP (1) | JP3462265B2 (en) |
Families Citing this family (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5614129A (en) * | 1993-04-21 | 1997-03-25 | California Institute Of Technology | Potassium lithium tantalate niobate photorefractive crystals |
| JPH08339002A (en) * | 1995-04-10 | 1996-12-24 | Ngk Insulators Ltd | Second harmonic wave generating element and its production |
| US6406647B1 (en) * | 1998-02-13 | 2002-06-18 | Mrinal Thakur | Method for preparation of single crystal films of organic second order optical materials |
| JP3828275B2 (en) * | 1998-03-20 | 2006-10-04 | パイオニア株式会社 | Wavelength conversion element and method for manufacturing wavelength conversion element |
| JP3681893B2 (en) * | 1998-03-20 | 2005-08-10 | パイオニア株式会社 | Wavelength conversion element and method for manufacturing wavelength conversion element |
| JPH11326967A (en) * | 1998-05-12 | 1999-11-26 | Ngk Insulators Ltd | Second harmonic generation element |
| DE69924423T2 (en) * | 1998-05-27 | 2006-03-09 | Ngk Insulators, Ltd., Nagoya | Device for generating the second harmonic wave |
| JP2000131546A (en) | 1998-10-26 | 2000-05-12 | Pioneer Electronic Corp | Production of ridge type three-dimensional waveguide |
| US6994800B1 (en) | 1999-04-29 | 2006-02-07 | President And Fellows Of Harvard College | Liquid precursors for formation of materials containing alkali metals |
| WO2000067300A1 (en) * | 1999-04-29 | 2000-11-09 | President And Fellows Of Harvard College | Liquid precursors for formation of materials containing alkali metals |
| US6513226B2 (en) | 2000-03-28 | 2003-02-04 | Ngk Insulators, Ltd. | Method of manufacturing film structure, method of manufacturing optical waveguide substrate and method of manufacturing second harmonic generation device |
| US6429103B1 (en) * | 2000-04-13 | 2002-08-06 | Motorola, Inc. | MOCVD-grown emode HIGFET buffer |
| GB2372110B (en) * | 2000-09-26 | 2003-12-31 | Bookham Technology Plc | Controlling birefringence in an optical waveguide and in an arrayed waveguide grating |
| US6792189B2 (en) * | 2001-05-13 | 2004-09-14 | Nippon Telegraph And Telephone Corporation | Optical waveguide and method of manufacture |
| CN100378567C (en) * | 2003-03-11 | 2008-04-02 | 日本碍子株式会社 | Wavelength converting devices |
| JP2004295088A (en) * | 2003-03-11 | 2004-10-21 | Ngk Insulators Ltd | Wavelength conversion element |
| CN100353193C (en) * | 2003-07-16 | 2007-12-05 | 日本电信电话株式会社 | Optical waveguide material and optical waveguide |
| JP4652122B2 (en) | 2005-05-18 | 2011-03-16 | 株式会社日立製作所 | Projection-type image display device, optical member and optical unit used therefor |
| US10222677B2 (en) | 2014-02-24 | 2019-03-05 | Rockley Photonics Limited | Optoelectronic device |
| US10928659B2 (en) | 2014-02-24 | 2021-02-23 | Rockley Photonics Limited | Optoelectronic device |
| GB2564158B (en) | 2017-07-05 | 2019-12-18 | Rockley Photonics Ltd | Optoelectronic device |
| US10216059B2 (en) | 2015-03-05 | 2019-02-26 | Rockley Photonics Limited | Waveguide modulator structures |
| US11150494B2 (en) | 2015-03-05 | 2021-10-19 | Rockley Photonics Limited | Waveguide modulator structures |
| US10678115B2 (en) | 2015-03-05 | 2020-06-09 | Rockley Photonics Limited | Waveguide modulator structures |
| US10921616B2 (en) | 2016-11-23 | 2021-02-16 | Rockley Photonics Limited | Optoelectronic device |
| CN107533248A (en) | 2015-03-05 | 2018-01-02 | 洛克利光子有限公司 | waveguide modulator structure |
| US11101256B2 (en) | 2016-11-23 | 2021-08-24 | Rockley Photonics Limited | Optical modulators |
| CN109564362B (en) * | 2016-11-23 | 2023-12-12 | 洛克利光子有限公司 | Optoelectronic device |
| US11105975B2 (en) | 2016-12-02 | 2021-08-31 | Rockley Photonics Limited | Waveguide optoelectronic device |
| WO2018100172A1 (en) | 2016-12-02 | 2018-06-07 | Rockley Photonics Limited | Waveguide device and method of doping a waveguide device |
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| NL9002410A (en) * | 1990-11-06 | 1992-06-01 | Philips Nv | DEVICE FOR DOUBLING THE FREQUENCY OF A LIGHT WAVE. |
| NL9002791A (en) * | 1990-12-18 | 1992-07-16 | Philips Nv | DEVICE FOR DOUBLING THE FREQUENCY OF A LIGHT WAVE. |
| US5335062A (en) * | 1992-11-19 | 1994-08-02 | California Institute Of Technology | Apparatus for all-optical self-aligning holographic phase modulation and motion sensing and method sensing and method for sensing such phase modulation |
| US5422873A (en) * | 1993-03-25 | 1995-06-06 | California Institute Of Technology | Multiplexing and selective updatable fixing and erasing of volume holograms in photorefractive media and second harmonic generation in photorefractive media by optically induced periodic poling |
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Also Published As
| Publication number | Publication date |
|---|---|
| JPH086083A (en) | 1996-01-12 |
| US5581396A (en) | 1996-12-03 |
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